I looked into the weight vs size and single versus double issue when i was looking at buying my ledge.

I found the single bd ledge is 6.8kg vs 9kg for the double and 2.3kg for the single fly vs 2.7kg for the double fly. (simple fly)

all up 9.1kg for the single ledge/fly and 11.7kg for the double ledge/fly, 2.6kg difference

im happy to lug the extra 2.6kgs for the added comfort when soloing and convenience of only having to buy one ledge, im a big guy so the comfort is worth it and once your commited to taking a ledge your bags are gunna start getting heavy.

BD does make the heaviest ledges on the market but there durable and BIG!